Method and apparatus for retransmission

ABSTRACT

Aspects of the disclosure provide an apparatus for wireless communication. The apparatus includes a transceiver and a processing circuit. The transceiver is configured to transmit and receive wireless signals. The processing circuit is configured to detect an error of a previous scheduled transmission of data units from the apparatus to another apparatus. The other apparatus provides scheduled resources for transmission between the two apparatuses. Further, the processing circuit is configured to determine resources that are scheduled by the other apparatus for the apparatus to perform retransmission, and provide one or more of the data units in the previous scheduled transmission to the transceiver for retransmission using the scheduled resources.

This application is a continuation application of U.S. patentapplication entitled “METHOD AND APPARATUS FOR RETRANSMISSION”, having aSer. No. 16/421,136, having a filing date of May 23, 2019; which is acontinuation of U.S. patent application entitled “METHOD AND APPARATUSFOR RETRANSMISSION”, having a Ser. No. 15/589,774, having a filing dateof May 8, 2017; which claim the benefit of the U.S. provisionalapplication entitled “HE RETRANSMISSION RULES”, having a Ser. No.62/332,686, and having a filed date of May 6, 2016, having commoninventors, and having a common assignee, all of which is incorporated byreference in its entirety.

INCORPORATION BY REFERENCE

This present disclosure claims the benefit of U.S. ProvisionalApplication No. 62/332,686, “HE RETRANSMISSION RULES” filed on May 6,2016, which is incorporated herein by reference in its entirety.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent the work is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

A wireless local area network (WLAN) is used in home, school, officebuilding, store, shopping mall and the like to link two or more devicesusing wireless connections within a limited area to a network. The WLANallows users to move around within the limited area and still beconnected to the network. In addition, the WLAN can be configured toprovide connections to other network, such as, a wide area network,Internet and the like. Generally, WLANs are implemented based onstandards, such as IEEE 802.11 standards, and the like.

SUMMARY

Aspects of the disclosure provide an apparatus for wirelesscommunication. The apparatus includes a transceiver and a processingcircuit. The transceiver is configured to transmit and receive wirelesssignals. The processing circuit is configured to detect an error of aprevious scheduled transmission of data units from the apparatus toanother apparatus. The other apparatus provides scheduled resources fortransmission between the two apparatuses. Further, the processingcircuit is configured to determine resources that are scheduled by theother apparatus for the apparatus to perform retransmission, and provideone or more of the data units in the previous scheduled transmission tothe transceiver for retransmission using the scheduled resources.

In an embodiment, the processing circuit is configured to determine theresources that are scheduled by the other apparatus for retransmissionwithout using a backoff procedure.

In an example, the processing circuit is configured to detect the errorof the previous scheduled transmission at a sub channel level, andprovide the data units of the previous scheduled transmission to thetransceiver for retransmission using the scheduled resources.

In another example, the processing circuit is configured to detect theerror of a specific data unit in the data units in the previousscheduled transmission and provide the data unit to the transceiver forretransmission using the scheduled resources.

In an embodiment, the processing circuit is configured to provide arequest frame to the transceiver to send a resource request forretransmission to the other apparatus, receive a signal indicative ofthe resources that are scheduled by the other apparatus forretransmission and provide the one or more data units in the previousscheduled transmission to the transceiver for retransmission using thescheduled resources.

In another embodiment, the processing circuit is configured to usecontention to gain channel access for retransmission when the one ormore of the data units for retransmission are time sensitive.

Aspects of the disclosure provide a method for wireless communication.The method includes detecting, at an apparatus, an error of a previousscheduled transmission of data units from the apparatus to anotherapparatus that provides scheduled resources for transmission between thetwo apparatuses, determining resources that are scheduled by the otherapparatus for the apparatus to perform retransmission, andre-transmitting one or more of the data units in the previous scheduledtransmission using the scheduled resources.

Aspects of the disclosure provide an apparatus for wirelesscommunication. The apparatus includes a transceiver and a processingcircuit. The transceiver is configured to transmit and receive wirelesssignals. The processing circuit is configured to schedule resources of acommunication channel to one or more other apparatuses by sub channels,provide data units for the one or more other apparatus to thetransceiver to transmit in a first transmission using the scheduledresources, detect an error in a channel level and provide, to thetransceiver, one or more data units selected from the data units in thefirst transmission based on the channel level for retransmission usingthe scheduled resources.

Aspects of the disclosure provide a method for wireless communication.The method includes scheduling, by an apparatus, resources of acommunication channel to one or more other apparatuses by sub channels,transmitting data units to the one or more other apparatus in a firsttransmission using the scheduled resources, detecting an error in achannel level, and retransmitting one or more data units selected fromthe data units in the first transmission based on the channel levelusing the scheduled resources.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of this disclosure that are proposed as exampleswill be described in detail with reference to the following figures,wherein like numerals reference like elements, and wherein:

FIG. 1 shows a block diagram of a network 100 according to an embodimentof the disclosure;

FIG. 2 shows a flow chart outlining a process 200 according to anembodiment of the disclosure;

FIG. 3 shows a flow chart outlining a process 300 according to anembodiment of the disclosure; and

FIGS. 4-8 show plots illustrating scheduling based data exchangesequences according to embodiments of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a block diagram of a network 100 according to an embodimentof the disclosure. The network 100 includes a first electronic device110 and one or more second electronic devices 160 a-160 n thatcommunicate using scheduling based transmission. In the FIG. 1 example,the first electronic device 110 is the scheduler configured to scheduleresources (e.g., timing, frequency, resource element, resource unit) ofa communication channel for transmission between the first electronicdevice 110 and the second electronic devices 160 a-160 n, and the secondelectronic devices 160 a-160 n are schedulees configured to performtransmission according to the scheduled resources by the firstelectronic device 110. Further, the first electronic device 110 and thesecond electronic devices 160 a-160 n are configured to performscheduling-based retransmission in response to errors in the previoustransmissions.

The network 100 includes interconnections that are implemented using anysuitable network technology, such wired, wireless, a local area network(LAN), a wireless LAN (WLAN), a fiber optical network, a wide areanetwork (WAN), a peer-to-peer network, the Internet, and the like. In anexample, the first electronic device 110 and the second electronicdevices 160 a-160 n are in a basic service set (BSS) 101 that isimplemented using WLAN technology to interconnect the first device 110and the second devices 160 a-160 n. The network 100 includes othersuitable interconnections (not shown), such as a LAN, a fiber opticalnetwork, and the like to provide connections for the BSS 101 to beconnected to for example Internet.

In an embodiment, the BSS 101 is an infrastructure type basic serviceset. The first electronic device 110 is an access point (AP) device, andthe second electronic devices 160-a-160 n are station (STA) devices. Thesecond electronic devices 160 a-160 n communicate through the firstdevice 110, and the first device 110 includes network hardware andsoftware configured to serve as a bridge to allow wireless compliantdevices, such as the second electronic devices 160 a-160 n to connect toother part of the network 100.

Each of the second electronic devices 160 a-160 n in the network 100 canbe any suitable device, such as a desktop computer, a laptop computer, atablet computer, a smart phone, a personal digital assistant (PDA), asmart watch, a smart camera, a smart TV, a smart voice recorder, awearable device, and the like. According to an aspect of the disclosure,the second electronic devices 160 a-160 n in the network 100 areimplemented using the same version or different versions of a wirelessstandard, such as various IEEE 802.11 standards.

In the FIG. 1 example, the second electronic devices 160 a-160 n shareresources of a communication channel for a transmission, and the firstelectronic device 110 is configured to schedule the resources of thetransmission (e.g., timing, frequency, resource element, resource unit)to data unit (e.g., frame) exchanges between the first electronic device110 and the second electronic devices 160 a-160 n. The second electronicdevices 160 a-160 n are configured to perform transmission according tothe scheduled resources. For example, at a time, the first electronicdevice 110 plans to transmit data units respectively to a group ofsecond electronic devices among the second electronic devices 160 a-160n. The group of second electronic devices involved in a transmission isreferred to as targeted second electronic devices. The first electronicdevice 110 allocates resources of a transmission to the targeted secondelectronic devices, and performs a transmission to transmit data unitsrespectively to the targeted second electronic devices in the sametransmission according to the resource allocation of the transmission.

In another example, the first electronic device 110 schedules to receivedata units respectively targeted second electronic devices among thesecond electronic devices 160 a-160 n. The first electronic device 110allocates resources of a transmission to the targeted second electronicdevices. The targeted second electronic devices perform transmissions ina same time duration to respectively transmit data units to the firstelectronic device 110 according to resource allocation, and the firstelectronic device 110 receives the data units from the targeted secondelectronic devices in the same scheduled time duration for example.

According to an aspect of the disclosure, devices in the BSS 101, suchas the first electronic device 110, the second electronic devices 160a-160 n and the like are configured to transmit two or more data unitsusing an aggregation technique. In an embodiment, the first electronicdevice 110 aggregates two or more media access control (MAC) protocoldata units (MPDUs) to a same destination device (e.g., a secondelectronic device), and forms an aggregated MPDU (A-MPDU). For example,the first electronic device 110 collects Ethernet frames (e.g., dataunits) to the same destination device, and wraps each frame individuallywith a MAC header. Then the first electronic device 110 groups thewrapped frames into a larger frame. In the example, at the receptionside, the destination device can selectively acknowledge individualEthernet frames.

In an embodiment, the first electronic device 110 is configured toschedule the resources of the communication channel to targeted secondelectronic devices among the second electronic devices 160 a-160 n bysub channels, and each sub channel is configured to transmit one or moredata units. In an example, the communication channel is allocated in thefrequency domain as frequency bands. A frequency band is then allocatedas a sub channel in an example.

In another example, the communication channel is allocated in the timedomain as sub streams of a full stream. A sub stream is then allocatedas a sub channel in an example. In another example, the communicationchannel is configured using orthogonal frequency-division multiplexing(OFDM) technology. In an example, a group of OFDM symbols is allocatedas a sub channel.

According to an aspect of the disclosure, transmission failures happenat various channel level, such as a full channel level, a sub channellevel, a data unit level, and the like. The first electronic device 110and the second electronic devices 160 a-160 n are configured to detecttransmission errors at the different channel levels, and performscheduling-based retransmission in response to transmission errors basedon the detected channel levels of the transmission errors.

Specifically, in the FIG. 1 example, the first electronic device 110includes a first transceiver circuit 113 and a first processing circuit120 coupled together as shown in FIG. 1. In the example, the firsttransceiver circuit 113 includes a first receiving circuit 116 and afirst transmitting circuit 115 that are both coupled to a first antenna114, and the first processing circuit 120 includes a firstretransmission controller 130 that is scheduler based retransmissioncontroller.

The first transceiver circuit 113 is configured to receive and transmitwireless signals. For example, the first receiving circuit 116 isconfigured to generate electrical signals in response to capturedelectromagnetic waves by the first antenna 114, process the electricalsignals to extract digital streams from the electrical signals. In anexample, the first transmitting circuit 115 is configured to receivedigital streams, such as management frames, data frames, and the likefrom for example the first processing circuit 120, generate radiofrequency (RF) signals to carry the digital streams, and emitelectromagnetic waves in the air via the first antenna 114 to transmitwireless signals that carry the digital streams.

The second electronic device 160 a includes a second transceiver circuit163 a and a second processing circuit 170 a coupled together. The secondtransceiver circuit 163 a includes a second transmitting circuit 165 aand a second receiving circuit 166 a that are both coupled to a secondantenna 164 a. The second processing circuit 170 a includes a secondretransmission controller 180 a that is schedulee based retransmissioncontroller. Other second electronic devices are configured similarly asthe second electronic device 160 a.

The second transceiver circuit 163 a is configured to receive andtransmit wireless signals. For example, the second receiving circuit 166a is configured to generate electrical signals in response to capturedelectromagnetic waves by the second antenna 164 a, process theelectrical signals to extract digital streams from the electricalsignals. In an example, the second transmitting circuit 165 a isconfigured to receive digital streams, such as management frames, dataframes, and the like from for example the processing circuit 170 a,generate radio frequency (RF) signals to carry the digital streams, andemit electromagnetic waves in the air via the second antenna 164 a totransmit wireless signals that carry the digital streams.

According to an aspect of the disclosure, the first retransmissioncontroller 130 and the second retransmission controllers 180 a-n areconfigured to detect transmission errors at the different channellevels, and control scheduling-based retransmission in response totransmission errors based on the detected channel levels of thetransmission errors.

In an embodiment, the first electronic device 110 and the secondelectronic devices 160 a-160 n are implemented according to an opensystems interconnection model (OSI model) with a plurality of layers,such as a physical (PHY) layer, a media access control (MAC) layer, anetwork layer, and the like from bottom up. In an example, the PHY layerincludes transceiver circuits and baseband processing circuits in theprocessing circuits. In an embodiment, the first retransmissioncontroller 130 and the second retransmission controllers 180 a-180 n areimplemented in the MAC layer using circuits. In another embodiment, thefirst retransmission controller 130 and the second retransmissioncontrollers 180 a-180 n are implemented as processors executing softwareinstructions.

It is noted that while single antenna per device is used in the FIG. 1example, the network 100 can be suitably modified to use multiple input,multiple output (MIMO) antenna technology.

According to an aspect of the disclosure, the first retransmissioncontroller 130 detects an error in the full channel level when aspecific timer expires. In an example, the specific timer tracks a timeduration from a transmission to a proper reply, and when the time islonger than a threshold, the specific timer expires or has a timeout. Inan example, the specific timer measures a time duration from atransmission of data units to a reception of a proper acknowledgement(ACK) frame, and is referred to as an ACK timer. In another example, thespecific timer measures a time duration from a transmission of a requestto send (RTS) frame to a reception of a clear to send (CTS) frame, andis referred to as a CTS timer.

In another embodiment, the first retransmission controller 130 detectsan error in the full channel level when the first electronic device 110receives unscheduled transmission. In an example, the first electronicdevice 110 transmits data units, and expects reception of an ACK frame.When the first electronic device 110 receives frame other than the ACKframe, the first retransmission controller 130 detects an error in thefull channel level. In another example, the first electronic device 110transmits a RTS frame, and expects reception of a CTS frame. When thefirst electronic device 110 receives frame other than the CTS frame, thefirst retransmission controller 130 detects an error in the full channellevel. In another example, the first electronic device 110 transmits atrigger signal that is indicative of resources allocation to targetedsecond electronic devices, and expects reception of uplink transmissionfrom the targeted second electronic devices. When the first electronicdevice 110 receives uplink transmission from a second electronic devicethat is not in the targeted second electronic devices, the firstretransmission controller 130 detects an error in the full channellevel.

In another embodiment, the first retransmission controller 130 detectsan error in a sub channel level when the first electronic device 110fails to receive uplink transmission from one of the targeted secondelectronic devices. In an example, the first electronic device 110transmits a trigger signal that is indicative of resources allocation totargeted second electronic devices, and expects reception of uplinktransmission from the targeted second electronic devices. When the firstelectronic device 110 fails to receive uplink transmission from one ofthe targeted second electronic devices, the first retransmissioncontroller 130 detects an error in the sub channel level.

In another embodiment, the first retransmission controller 130 detectsan error in a data unit (e.g., MPDU) level when the first retransmissioncontroller 130 detects one or more unacknowledged data units in a blockacknowledgement (BA). In an example, the first electronic device 110transmits data units to a targeted second electronic device, andreceives a BA. When the first retransmission controller 130 detects thatthe BA does not include acknowledgement for one or more of thetransmitted data units, the first retransmission controller 130 detectsan error in the data unit level.

Additionally, the first retransmission controller 130 is configured tocontrol retransmission based on the transmission error levels. In anexample of an error in the full channel level, the first retransmissioncontroller 130 is configured to use a backoff procedure withexponentially increased (e.g., doubled) contention window to gain a nextchannel access. Generally, the contention window is set according toexpected communication traffic. In an example, the error in the fullchannel level is indicative of heavier communication traffic, thus thecontention window is set wider. The first retransmission controller 130randomly selects a value within the contention window, and sets abackoff counter for the backoff procedure. The backoff procedure is usedto defer an access to transmission medium (e.g., a communicationchannel) when the transmission medium is idle.

When the first electronic device 110 gains the next channel access, inan example, the first retransmission controller 130 controls theprocessing circuit 120 to provide the same A-MPDU to the firsttransmitting circuit 115 for transmission. In another example, the firstretransmission controller 130 controls the processing circuit 120 toprovide a different A-MPDU to the first transmitting circuit 115 fortransmission.

In an example of an error in the sub channel level, the firstretransmission controller 130 does not invoke a backoff procedure. In anexample, the first retransmission controller 130 identifies the targetedsecond electronic device in which the error in the sub channel levelhappens, and causes a retransmission of data units to the targetedsecond electronic device in a next scheduled transmission.

In another example, a trigger signal is sent by the first electronicdevice 110 to allocate a sub channel to a targeted second electronicdevice. The first transmission controller 130 detects an error in thesub channel level when there is no uplink response in the sub channelallocated to the targeted second electronic device. In the example, thefirst retransmission controller 130 identifies the targeted secondelectronic device, and causes a transmission of a trigger signal that isindicative of resources allocation to the targeted second electronicdevice in a next scheduled transmission. The resource allocation to thetargeted second electronic device can be the same as the previoustransmission or can be different from the previous transmission.

In an example of an error in the data unit level, the firstretransmission controller 130 does not invoke a backoff procedure. In anexample, the first retransmission controller 130 identifies the targetedsecond electronic device in which the error happens and identifies oneor more data units that are unacknowledged. Then, the firstretransmission controller 130 causes a retransmission of the identifieddata units to the targeted second electronic device in a next scheduledtransmission.

According to an aspect of the disclosure, on the STA device side, usingthe second electronic device 160 a as an example, the secondretransmission controller 180 a detects an error in the sub channellevel when a specific timer expires. In an example, the specific timertracks a time duration from a transmission to a proper reply, and whenthe time is longer than a threshold, the specific timer expires or has atimeout. In an example, the specific timer measures a time duration froma transmission of data units to a reception of a proper acknowledgement(ACK), and is referred to as an ACK timer.

In another embodiment, the second retransmission controller 180 adetects an error in the sub channel level when the second electronicdevice 160 a receives unscheduled transmission. In an example, thesecond electronic device 160 a transmits data units, and expectsreception of an ACK frame. When the second electronic device 160 areceives frame other than the ACK frame, the second retransmissioncontroller 180 a detects an error in the sub channel level.

In another embodiment, the second retransmission controller 180 adetects an error in a data unit (e.g., MPDU) level when the secondretransmission controller 180 a detects one or more unacknowledgedframes in a block acknowledgement (BA). In an example, the secondelectronic device 160 a transmits data units (e.g., an A-MPDU havingaggregated MPDUs) to the first electronic device 110, and receives a BA.When the second retransmission controller 180 a detects that the BA doesnot include acknowledgement for one or more data units (MPDUs) of thetransmitted data units, the second retransmission controller 180 adetects an error in the data unit level.

Additionally, the second retransmission controller 180 a is configuredto control retransmission based on the transmission error levels. In anexample, when resources allocation of a next scheduled uplinktransmission is available for the second electronic device 160 a, thesecond retransmission controller 180 a causes a retransmission of dataunits to the first electronic device 110 in the next scheduled uplinktransmission.

In another example, the second retransmission controller 180 a causes aresource request to be sent to the first electronic device 110. In anexample, the second retransmission controller 180 a uses an orthogonalfrequency-division multiple access (OFDMA) opportunity to send aresource request frame to the first electronic device 110. In anotherexample, the second retransmission controller 180 a uses OFDMAopportunity to send a buffer status report frame. In an example, thesecond retransmission controller 180 a counts unacknowledged data unitsin the buffer as pending uplink traffic. The buffer status report frameis indicative of a resource request for uplink transmission. In anotherexample, the second retransmission controller 180 a inserts a resourcerequest for uplink transmission in an acknowledgement frame for downlinktransmission, and provides the acknowledgement frame for downlinktransmission to the second transmitting circuit 165 a to transmit to thefirst electronic device 110.

In another example, the second retransmission controller 180 a uses acontention based channel access technique, such as enhanced distributedchannel access (EDCA) and the like. In an example, when the data unitsare time sensitive traffic, the second retransmission controller 180 auses the contention based channel access technique to gain an uplinktransmission opportunity that is earlier than a scheduled uplinktransmission.

FIG. 2 shows a flow chart outlining a process 200 according to anembodiment of the disclosure. In an example, the process 200 is executedby the first electronic device 110 in the FIG. 1 example. The processstarts at S201 and proceeds to S210.

At S210, a downlink transmission is performed. In the FIG. 1 example,the first electronic device 110 transmits data units to the secondelectronic device 160 a-160 n. In an example, the first electronicdevice 110 gains channel access of a communication channel. Then thefirst electronic 110 uses the communication channel to transmit downlink(DL) signals carrying data units (frames) from the first electronicdevice 110 to the second electronic devices 160 a-160 n. In an example,the first electronic device 110 allocates resources of the communicationchannel to the targeted second electronic devices by sub channels, anduses the sub channels to respectively carry data units to the respectivetargeted second electronic devices.

At S220, an error is detected. In the FIG. 1 example, the firstelectronic device 110 detects a transmission error at various channellevel, such as a full channel level, a sub channel level and a data unitlevel, and the like.

At S230, the process proceeds based on the channel level of the error.When the error is at the full channel level, the process proceeds toS240; otherwise the process proceeds to S260.

At S240, a backoff procedure is performed to gain a next channel access.In an example, the error in the full channel level is indicative ofheavy communication traffic, thus the first electronic device 110doubles the contention window. The first electronic device 110 randomlyselects a value within the contention window, and sets a backoff counterfor the backoff procedure. The backoff procedure is used to defer a nextaccess to transmission medium (e.g., a communication channel) when thetransmission medium is idle.

At S250, a retransmission of previously failed data units is performed.In an example, the first electronic device 110 retransmits the dataunits in the previous transmission. Then the process proceeds to S299and terminates.

At S260, the previously failed data units are retransmitted in a nextscheduled downlink transmission to the targeted second electronicdevices. In an example of an error in the sub channel level, the firstretransmission controller 130 does not invoke a backoff procedure. In anexample, the first retransmission controller 130 identifies the targetedsecond electronic device in which the error in the sub channel levelhappens, and causes a retransmission of data units to the targetedsecond electronic device in a next scheduled downlink transmission.

In an example of an error in the data unit level, the firstretransmission controller 130 does not invoke a backoff procedure. In anexample, the first retransmission controller 130 identifies the targetedsecond electronic device in which the error happens and identifies oneor more data units without acknowledgement. Then, the firstretransmission controller 130 causes a retransmission of the identifieddata units to the targeted second electronic device in a next scheduleddownlink transmission. Then the process proceeds to S299 and terminates.

FIG. 3 shows a flow chart outlining a process 300 according to anembodiment of the disclosure. In an example, the process 300 is executedby a second electronic device, such as the second electronic device 160a. The process starts at S301 and proceeds to S310.

At S310, uplink resource allocation is received. In an example, thesecond electronic device 160 a receives a trigger signal that isindicative of uplink resource allocation. For example, a sub channel isallocated to the second electronic device 160 a.

At S320, data units are transmitted according to resource allocation forthe uplink transmission. In an example, the second electronic device 160a aggregates MPDUs into an A-MPDU, and transmits signals that carry theA-MPDU to the first electronic device 110 using the allocated resourcein the uplink transmission.

At S330, an error is detected. The second electronic device 160 adetects errors in the sub channel level and the data unit level.

At S340, the process proceeds based on whether uplink resourceallocation is available for retransmission. When the uplink resourceallocation is available for retransmission, the process proceeds toS390; otherwise, the process proceeds to S350.

At S350, the process proceeds based on whether the retransmission iseligible for contention based channel access (e.g., EDCA). When theretransmission is eligible for the contention based channel access, theprocess proceeds to S360; otherwise, the process proceeds to S370.

At S360, contention is used to gain channel access for retransmission,and the retransmission is performed. Then the process proceeds to S399and terminates.

At S370, a request is send to the first electronic device 110 to requestresource for retransmission.

At S380, resource allocation for retransmission is received.

At S390, retransmission is performed based on the resource allocation.Then, the process proceeds to S399 and terminates.

FIG. 4 shows a plot 400 illustrating a scheduling based data exchangesequence example in the network 100 according to embodiments of thedisclosure. In an example, the first electronic device 110 is the APdevice, the second electronic devices 160 a-160 n are STA devices, theSTA0-STA3 are the targeted STA devices. In the FIG. 4 example, the APgains channel access and uses a communication channel to transmitinformation to the targeted STA devices STA0-STA3.

In the FIG. 4 example, the AP allocates a first sub channel SUB-CH1 toSTA0, a second sub channel SUB-CH2 to STA1, a third sub channel SUB-CH3to STA2, and a fourth sub channel SUB-CH4 to STA3.

At t1, the first electronic device 110 gains the channel access for thecommunication channel.

At t2, the first electronic device 110 uses the communication channel toperform downlink (DL) transmission to transmit data units from the firstelectronic device 110 to the targeted STA devices. Specifically, thefirst sub channel SUB-CH1 carries an A-MPDU 411 to the STA0; the secondsub channel SUB-CH2 carries an A-MPDU 412 to the STA1; the third subchannel SUB-CH3 carries an A-MPDU 413 to the STA2; and the fourth subchannel SUB-CH4 carries an A-MPDU 414 to the STA3.

At t3, the first electronic device 110 expects uplink transmissioncarrying block acknowledgements (BAs) from the targeted STA devicesSTA0-STA3. The BAs are used to indicate whether MPDUs are received withsuccess in an example. In the FIG. 4 example, the first sub channelSUB-CH1 carries a BA 421 that is used to indicate whether MPDUs in theA-MPDU 411 are successfully received by the STA0; the second sub channelSUB-CH2 carries a BA 422 that is used to indicate whether MPDUs in theA-MPDU 412 are successfully received by the STA1; the third sub channelSUB-CH3 carries a BA 423 that is used to indicate whether MPDUs in theA-MPDU 413 are successfully received by the STA2; and the fourth subchannel SUB-CH4 carries a BA 424 that is used to indicate whether MPDUsin the A-MPDU 414 are successfully received by the STA3.

However, errors can happen, and the first electronic device 110 isconfigured to detect errors at different levels, such as a full channellevel, a sub channel level, a MPDU level, and the like.

In an example, the first electronic device 110 detects an error at thefull channel level when a specific timer, such as the ACK timer, the CTStimer, and the like expires the first electronic device 110 receives theuplink signals. In another example, the first electronic device 110detects an error at the full channel level when the first electronicdevice 110 receives something else other than the expected BAs.

In another example, the first electronic device 110 detects an error atthe sub channel level when the first electronic device 110 receives asubset of BAs in the uplink signals, and fails to receive one or moreBAs from STAs. For example, the first electronic device 110 fails toreceive the BA 424 from the fourth sub channel SUB-CH4, thus the firstelectronic device 110 detects an error in the fourth sub channelSUB-CH4.

In another example, the first electronic device 110 detects an error atthe data unit level when the first electronic device 110 detectsunacknowledged MPDUs. For example, the first electronic device 110aggregates three MPDUs in an A-MPDU 414, and transmits the A-MPDU 414 tothe STA3 in the fourth sub channel SUB-CH4. However, the BA 424 that isreceived from the fourth sub channel SUB-CH4 includes acknowledgement oftwo out of three MPDUs. Thus, the first electronic device 110 detects anerror at the data unit level.

The first electronic device 110 then re-transmits based on the channellevel of the error. In an example of an error in the full channel level,the first electronic device 110 uses a backoff procedure withexponentially increased (e.g., double) contention window to gain channelaccess. When the first electronic device 110 gains the channel access,in an example, the first electronic device 110 retransmits the same dataunits. In another example, the first electronic device 110 transmits newA-MPDU that aggregates the previously unacknowledged MPDUs.

In an example of an error in the sub channel, the first electronicdevice 110 does not invoke backoff procedure. In an example, the firstelectronic device 110 identifies the targeted second electronic devicein which the error in the sub channel level happens, and causes aretransmission of data units to the targeted second electronic device ina next scheduled downlink transmission.

FIG. 5 shows a plot 500 illustrating a scheduling based data exchangesequence example in the network 100 according to embodiments of thedisclosure. In an example, the first electronic device 110 is the APdevice, the second electronic devices 160 a-160 n are STA devices, theSTA0-STA3 are the targeted STA devices. In the FIG. 5 example, the APgains channel access and schedules the targeted STA devices STA0-STA3 toperform uplink transmission.

In the FIG. 5 example, the AP allocates a first sub channel SUB-CH1 toSTA0, a second sub channel SUB-CH2 to STA1, a third sub channel SUB-CH3to STA2, and a fourth sub channel SUB-CH4 to STA3.

In the FIG. 5 example, the AP first gains channel access, and sends atrigger signal to the STA devices. The trigger signal carries variouscontrol information for the scheduled uplink transmission, such astiming, resource allocation, MCS, and the like. In an example, thetrigger signal is a broadcast signal. In an example, the trigger signalincludes allocation information, for example, the first sub channelSUB-CH1 allocated to STA0, the second sub channel SUB-CH2 allocated toSTA1, the third sub channel SUB-CH3 allocated to STA2, and the fourthsub channel SUB-CH4 allocated to STA3.

At t1, the first electronic device 110 gains the channel access for thecommunication channel.

At t2, the first electronic device 110 uses the communication channel totransmit a trigger signal carrying various control information for thescheduled uplink transmission. In an example, the trigger signal is abroadcast signal.

At t3, the targeted STA devices perform the scheduled uplinktransmission according to the resource allocation. Specifically, thefirst sub channel SUB-CH1 carries A-MPDU 521 from the STA0 to AP; thesecond sub channel SUB-CH2 carries A-MPDU 522 from the STA1 to AP; thethird sub channel SUB-CH3 carries A-MPDU 523 from the STA2 to AP; andthe fourth sub channel SUB-CH4 carries A-MPDU 524 from the STA3 to AP.

At t4, the first electronic device 110 transmits multi-user Bas (M-BAs)to the STA0-STA3 in the downlink transmission. The M-BAs are used toindicate whether MPDUs are received with success. In the FIG. 5 example,the first sub channel SUB-CH1 carries a M-BA 531 to indicate whether theMPDUs in the A-MPDU 521 are received with success to the STA0; thesecond sub channel SUB-CH2 carries a M-BA 532 to indicate whether theMPDUs in the A-MPDU 522 are received with success to the STA1; the thirdsub channel SUB-CH3 carries a M-BA 533 to indicate whether the MPDUs inthe A-MPDU 523 are received with success to the STA2 and the fourth subchannel SUB-CH4 carries a M-BA 534 to indicate whether the MPDUs in theA-MPDU 524 are received with success to the STA3.

However, errors can happen, and both the first electronic device 110 andthe second electronic devices 160 a-160 n are configured to detecterrors at different levels and retransmit accordingly.

At the AP side, in an example, the first electronic device 110 detectsan error at the full channel level when a specific timer, such as theACK timer, expires before the first electronic device 110 receives theuplink transmission. In another example, the first electronic device 110detects an error at the full channel level when the first electronicdevice 110 receives something else other than the expected A-MPDUs. Inanother example, the first electronic device 110 detects an error at thesub channel level when the first electronic device 110 receives A-MPDUsin a subset of sub channels in the uplink transmission, and fails toreceive A-MPDU from a sub channel assigned to a targeted STA. Forexample, the first electronic device 110 fails to receive A-MPDU 524from the fourth sub channel SUB-CH4, thus the first electronic device110 detects an error in the fourth sub channel SUB-CH4.

At the STA side, in an example, the second electronic device 160 adetects a reception error at a sub channel level when the ACK timer istime out before the second electronic device 160 a receives the M-BAfrom the AP. In another example, the second electronic device 160 adetects an error at the sub channel level when the second electronicdevice 160 a receives something else other than the expected M-BA. Inanother example, the second electronic device 160 a detects an error atthe data unit level when the second electronic device 160 a detectsunacknowledged MPDUs. For example, the second electronic device 160 aaggregates three MPDUs in the A-MPDU 524, and transmits the A-MPDU 524to the AP in the fourth sub channel SUB-CH4. However, the M-BA 534includes acknowledgement of two out of three MPDUs. Thus, the secondelectronic device 160 a detects an error at the data unit level.

The first electronic device 110 then re-transmits based on the channellevel of the error. In an example of an error in the full channel level,the first electronic device 110 uses a backoff procedure withexponentially increased (e.g., double) contention window to gain channelaccess. When the first electronic device 110 gains the channel access,in an example, the first electronic device 110 retransmits, for example,the same trigger signal and the M-BAs. In another example, the firstelectronic device 110 transmits a new trigger signal, and M-BAs.

In an example of an error in the sub channel level, the first electronicdevice 110 does not invoke the backoff procedure. In an example, thefirst electronic device 110 identifies the targeted STA device in whichthe error in the sub channel level happens. When the first electronicdevice 110 schedules a next uplink transmission, the first electronicdevice 110 allocates uplink resource to the identified targeted STAdevice, transmits a trigger signal to inform the uplink resourceallocation to the identified targeted STA device.

At the STA side, using the second electronic device 160 a as an example,when the second electronic device 160 a detects an error, the secondelectronic device 160 a does not invoke backoff procedure. Further, inan example, the second electronic device 160 a retransmits thepreviously unacknowledged MPUs in a next scheduled uplink transmission.

In another example, when the unacknowledged MPUs are time sensitive, thesecond electronic device 160 a contents for channel access in order toretransmit the previously unacknowledged MPUs earlier than the nextscheduled uplink transmission.

FIG. 6 shows a plot 600 illustrating a scheduling based data exchangesequence example in the network 100 according to an embodiment of thedisclosure. In an example, the first electronic device 110 is the APdevice, the second electronic devices 160 a-160 n are STA devices, theSTA0-STA3 are the targeted STA devices. In the FIG. 6 example, the APdevice gains channel access and schedules the targeted STA devicesSTA0-STA3 to perform uplink transmission.

In the FIG. 6 example, the AP allocates a first sub channel SUB-CH1 toSTA0, a second sub channel SUB-CH2 to STA1, a third sub channel SUB-CH3to STA2, and a fourth sub channel SUB-CH4 to STA3.

At t1, the first electronic device 110 gains the channel access for thecommunication channel.

At t2, the first electronic device 110 uses the communication channelfor a downlink transmission to transmit signals, such as trigger signaland data units, from the first electronic device 110 to the targeted STAdevices. The trigger signal carries control information for scheduleduplink transmission. Specifically, the first downlink sub channelSUB-CH1 carries A-MPDU 611 and control information for scheduled uplinktransmission to the STA0; the second downlink sub channel SUB-CH2carries A-MPDU 612 and control information for scheduled uplinktransmission to the STA1; the third sub channel SUB-CH3 carries A-MPDU613 and control information for scheduled uplink transmission to theSTA2; and the fourth sub channel SUB-CH4 carries A-MPDU 614 and controlinformation for scheduled uplink transmission to the STA3.

At t3, targeted STA devices perform scheduled uplink transmissionaccording to the resource allocation, and transmit BAs for the downlinkdata units. Specifically, the first uplink sub channel SUB-CH1 carriesA-MPDU 621 from the STA0 to AP and BA for MPDUs in the A-MPDU 611; thesecond sub channel SUB-CH2 carries A-MPDU 622 from the STA1 to AP and BAfor MPDUs in the A-MPDU 612; the third sub channel SUB-CH3 carriesA-MPDU 623 from the STA2 to AP and BA for MPDUs in the A-MPDU 613; andthe fourth sub channel SUB-CH4 carries A-MPDU 624 from the STA3 to APand BA for MPDUs in the A-MPDU 614.

At t4, the first electronic device 110 transmits downlink signalscarrying M-BAs to the STA0-STA3. The M-BAs are used to indicate whetherMPDUs in the A-MPDUs 621-624 are received with success. In the FIG. 6example, the first sub channel SUB-CH1 carries a M-BA 631 to indicatewhether the MPDUs in the A-MPDU 621 are received with success to theSTA0; the second sub channel SUB-CH2 carries a M-BA 632 to indicatewhether the MPDUs in the A-MPDU 622 are received with success to theSTA1; the third sub channel SUB-CH3 carries a M-BA 633 to indicatewhether the MPDUs in the A-MPDU 623 are received with success to theSTA2; and the fourth sub channel SUB-CH4 carries a M-BA 634 to indicatewhether the MPDUs in the A-MPDU 624 are received with success to theSTA3.

However, errors can happen, and both the first electronic device 110 andthe second electronic devices 160 a-160 n are configured to detecterrors at different levels and retransmit accordingly.

At the AP side, in an example, the first electronic device 110 detectsan error at the full channel level when the ACK timer expires before thefirst electronic device 110 receives the uplink transmission. In anotherexample, the first electronic device 110 detects an error at the fullchannel level when the first electronic device 110 receives somethingelse other than the expected uplink transmission, such as BAs.

In another example, the first electronic device 110 detects an error atthe sub channel level when the first electronic device 110 receivesA-MPDUs in a subset of sub channels in the uplink transmission, andfails to receive A-MPDU from a sub channel assigned to a targeted STAdevice. For example, the first electronic device 110 fails to receiveA-MPDU from the fourth sub channel SUB-CH4, thus the first electronicdevice 110 detects the error in the fourth sub channel SUB-CH4.

At the STA side, in an example, the second electronic device 160 adetects an error at a sub channel level when the ACK timer expiresbefore the second electronic device 160 a receives the M-BA from the APdevice. In another example, the second electronic device 160 a detectsan error at the sub channel level when the second electronic device 160a receives something else other than the expected M-BAs. In anotherexample, the second electronic device 160 a detects an error at the dataunit level when the second electronic device 160 a detectsunacknowledged data units. For example, the second electronic device 160a aggregates three MPDUs in the A-MPDU 624, and transmits the A-MPDU 624to the AP in the fourth sub channel SUB-CH4. However, the M-BA 634 thatis received from the fourth sub channel SUB-CH4 includes acknowledgementof two out of three MPDUs. Thus, the second electronic device 160 adetects the error at the data unit level.

The first electronic device 110 then re-transmits based on the level ofreception errors. In an example of full channel reception error, thefirst electronic device 110 uses a backoff procedure with exponentiallyincreased (e.g., double) contention window to gain channel access. Whenthe first electronic device 110 gains the channel access, in an example,the first electronic device 110 retransmits the same trigger and dataunits. In another example, the first electronic device 110 transmitsdata units without trigger.

In an example of an error at the sub channel level, the first electronicdevice 110 does not invoke the backoff procedure. In an example, thefirst electronic device 110 identifies the targeted STA device in whichthe error in the sub channel level happens. When the first electronicdevice 110 schedules a next uplink transmission, the first electronicdevice 110 allocates uplink resource to the identified targeted STAdevice, transmits a trigger signal to inform the uplink resourceallocation to the identified targeted STA device. In an example, thefirst electronic device 110 transmits unacknowledged MPDUs in a nextscheduled downlink transmission.

In an example of an error at the data unit level, the first electronicdevice 110 does not invoke the backoff procedure. The first electronicdevice 110 identifies the targeted STA device in which the errorhappens, and transmits unacknowledged MPDUs in a next scheduled downlinktransmission to the targeted STA device.

At the STA side, using the second electronic device 160 a as an example,when the second electronic device 160 a detects error in the sub channellevel or the data unit level, the second electronic device 160 a doesnot invoke backoff procedure. In an example, the second electronicdevice 160 a retransmits the previously unacknowledged MPUs in nextscheduled uplink transmission. In another example, when theunacknowledged MPUs are time sensitive, the second electronic device 160a contents for channel access in order to retransmit the previouslyunacknowledged MPUs earlier than the next scheduled uplink transmission.

FIG. 7 shows a plot 700 illustrating a scheduling based data exchangesequence example in the network 100 according to an embodiment of thedisclosure. In an example, the first electronic device 110 is the APdevice, the second electronic devices 160 a-160 n are STA devices, theSTA0-STA3 are the targeted STA devices. In the FIG. 7 example, the APgains channel access and uses a communication channel to transmitinformation to the targeted STA devices STA0-STA3. The example in FIG. 7is similar to the example in FIG. 4 except an exchange of RTS frame andCTS frame.

At t1, the first electronic device 110 gains the channel access for thecommunication channel.

At t2, the first electronic device 110 transmits a RTS frame to thetargeted STA devices.

At t3, the targeted STA devices transmit signals carrying CTS frames.

At t4, the first electronic device 110 and the targeted STA devicesoperate similarly as FIG. 4 example at t2.

At t5, the first electronic device 110 and the targeted STA devicesoperate similarly as FIG. 4 example at t3.

The AP device and the targeted STA devices operate similarly as theexample in FIG. 4, the description of operations has been provided aboveand will be omitted here for clarity purposes.

In the FIG. 7 example, in an embodiment, the first electronic device 110detects an error at the full channel level when the CTS timer expiresbefore the first electronic device 110 receives any CTS frame. Inanother example, the first electronic device 110 detects an error at thefull channel level when the first electronic device 110 receives anyother frames than an expected CTS frame. In the embodiment, the firstelectronic device 110 retransmits the RTS frame in an example,

It is noted that, in an example, when the first electronic device 110receives any CTS frame, the first electronic device 110 does notretransmit the RTS frame.

FIG. 8 shows a plot 800 illustrating a scheduling based data exchangesequence example in the network 100 according to an embodiment of thedisclosure. In an example, the first electronic device 110 is the APdevice, the second electronic devices 160 a-160 n are STA devices, theSTA0-STA3 are the targeted STA devices. In the FIG. 8 example, the APgains channel access and uses a communication channel to transmitinformation to the targeted STA devices STA0-STA3. The example in FIG. 8is similar to the example in FIG. 5 except an exchange of RTS frame andCTS frame.

At t1, the first electronic device 110 gains the channel access for thecommunication channel.

At t2, the first electronic device 110 transmits a RTS frame to thetargeted STA devices.

At t3, the targeted STA devices transmit signals carrying CTS frames.

At t4, the first electronic device 110 and the targeted STA devicesoperate similarly as FIG. 5 example at t2.

At t5, the first electronic device 110 and the targeted STA devicesoperate similarly as FIG. 5 example at t3.

At t6, the first electronic device 110 and the targeted STA deviceoperates similarly as FIG. 5 example at t4.

The AP device and the targeted STA devices operate similarly to theexample in FIG. 5, the description of operations has been provided aboveand will be omitted here for clarity purposes.

In the FIG. 8 example, in an embodiment, the first electronic device 110detects an error at the full channel level when the CTS timer expiresbefore the first electronic device 110 receives any CTS frame. Inanother example, the first electronic device 110 detects an error at thefull channel level when the first electronic device 110 receives anyother frames than an expected CTS frame. In the embodiment, the firstelectronic device 110 retransmits the RTS frame in an example,

It is noted that, in an example, when the first electronic device 110receives any CTS frame, the first electronic device 110 does notretransmit the RTS frame.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), etc.

While aspects of the present disclosure have been described inconjunction with the specific embodiments thereof that are proposed asexamples, alternatives, modifications, and variations to the examplesmay be made. Accordingly, embodiments as set forth herein are intendedto be illustrative and not limiting. There are changes that may be madewithout departing from the scope of the claims set forth below.

What is claimed is:
 1. A method for wireless communication, the methodcomprising: transmitting by an apparatus, a trigger signal carryingcontrol information to allocate resources for scheduling a scheduleduplink transmission, the control information allocates resources to aset of at least one targeted apparatus for sending to the apparatus,data in the scheduled uplink transmission; performing error detection bythe apparatus to detect an error in the scheduled uplink transmission;if an error is detected as the result of the performing and if the erroris due to not receiving the scheduled uplink transmission, then:performing a backoff procedure by the apparatus, and after performingthe backoff procedure, transmitting by the apparatus, a second triggersignal carrying control information to allocate resources for schedulinga second scheduled uplink transmission; if an error is detected as theresult of the performing and if the error is due to receiving data fromat least one of the targeted apparatuses of the set in the scheduleduplink transmission but not receiving data from all of the targetedapparatuses of the set in the scheduled uplink transmission, thentransmitting by the apparatus, a second trigger signal carrying controlinformation to allocate resources for scheduling a second scheduleduplink transmission, where a backoff procedure is not performed by theapparatus responsive to the error prior to the transmitting the secondtrigger signal.
 2. The method of claim 1, wherein the controlinformation allocates resources to the set of at least one targetedapparatus for sending to the apparatus, data units in the scheduleduplink transmission.
 3. The method of claim 2, wherein the data unitsare characterized as media access control protocol data units (MPDU). 4.The method of claim 2, wherein the data units are characterized as aplurality of aggregated protocol data units (A-MPDU).
 5. The method ofclaim 1 where the backoff procedure uses an exponentially increasedcontention window to gain a next channel access.
 6. The method of claim1, wherein if the error is due to receiving data from at least one ofthe targeted apparatuses of the set in the scheduled uplink transmissionbut not receiving data from all of the targeted apparatuses of the setin the scheduled uplink transmission, then the second trigger signalincludes control information to allocate resources to targetedapparatuses of the set in which data was not received by the apparatusin the scheduled uplink transmission.
 7. The method of claim 1, whereinthe control information of the trigger signal allocates a subchannel ofa plurality of subchannels of the scheduled uplink transmission to eachtargeted apparatus of the set for sending data in the scheduled uplinktransmission.
 8. The method of claim 1, wherein the error is due to notreceiving the scheduled uplink transmission if an ACK timer expiresbefore the apparatus receives the scheduled uplink transmission.
 9. Themethod of claim 1, wherein the apparatus is characterized as an accesspoint.
 10. The method of claim 1, wherein if the error is due to notreceiving the scheduled uplink transmission, then the second triggersignal includes control information to allocate resources to each of thetargeted apparatuses of the set.
 11. An apparatus for wirelesscommunication, the apparatus comprising: a transceiver configured totransmit and receive wireless signals and a processing circuitconfigured to: initiate transmission of a trigger signal carryingcontrol information to allocate resources for scheduling a scheduleduplink transmission, the control information allocates resources to aset of at least one targeted apparatus for sending to the apparatus,data in the scheduled uplink transmission; perform error detection todetect an error in the scheduled uplink transmission; if an error isdetected and if the error is due to not receiving the scheduled uplinktransmission, then: invoke a backoff procedure, and after invoking thebackoff procedure, initiate transmission of a second trigger signalcarrying control information to allocate resources for scheduling asecond scheduled uplink transmission; if an error is detected and if theerror is due to receiving data from at least one of the targetedapparatuses of the set in the scheduled uplink transmission but notreceiving data from all of the targeted apparatuses of the set in thescheduled uplink transmission, then initiate transmission of a secondtrigger signal carrying control information to allocate resources forscheduling a second scheduled uplink transmission, where a backoffprocedure is not invoked responsive to the error prior to the secondtrigger signal being transmitted.
 12. The apparatus of claim 11, whereinthe control information allocates resources to the set of at least onetargeted apparatus for sending to the apparatus, data units in thescheduled uplink transmission.
 13. The apparatus of claim 12, whereinthe data units are characterized as media access control protocol dataunits (MPDU).
 14. The apparatus of claim 12, wherein the data units arecharacterized as a plurality of aggregated protocol data units (A-MPDU).15. The apparatus of claim 11, wherein the backoff procedure uses anexponentially increased contention window to gain a next channel access.16. The apparatus of claim 11, wherein if the error is due to receivingdata from at least one of the targeted apparatuses of the set in thescheduled uplink transmission but not receiving data from all of thetargeted apparatuses of the set in the scheduled uplink transmission,then the second trigger signal includes control information to allocateresources to targeted apparatuses of the set in which data was notreceived by the apparatus in the scheduled uplink transmission.
 17. Theapparatus of claim 11, wherein the control information of the triggersignal allocates a subchannel of a plurality of subchannels of thescheduled uplink transmission to each targeted apparatus of the set forsending data in the scheduled uplink transmission.
 18. The apparatus ofclaim 11 further comprising: an ACK timer; wherein the error is due tonot receiving the scheduled uplink transmission if the ACK timer expiresbefore the apparatus receives the scheduled uplink transmission.
 19. Theapparatus of claim 11, wherein the apparatus is characterized as anaccess point.
 20. The apparatus of claim 11, wherein if the error is dueto not receiving the scheduled uplink transmission, then the secondtrigger signal includes control information to allocate resources toeach of the targeted apparatuses of the set.